12v System Goes on strike!

[Furlo]

We've got a Dethleffs Trend which we store on the drive. We've had it for only a year. Recently a couple of times, when I go out to check it, the 12v system has switched itself off & won't come back on using the rocker switch on the control panel.
If I attach shore, even for a few seconds, power 12v supply comes straight back & all is well.

I've had the 12v system cut off before while we've been in the van, I think it's caused by the voltage dropping to a threshold triggering the van to cut off the power (I was pumping the water through the hot water system). However, in that case the 12v was brought back online by just hitting the switch on the control panel.

The leisure battery still has over 90% capacity (recently fitted a Victron Smart Shunt) & looks okay.
The draw on the 12v system is barely a few watts (if that).
The leisure battery is a Varta Dual Purpose AGM.

Does anyone have an idea what causes this behaviour?
I don't mind so much the power cutting, it's the fact I can't get it back without shore power is the concern... Although I didn't try starting the engine - that may bring it back to life. Still, I'd like to know what's causing it.

Many Thanks!

 

[denisejoe]

Have you tried measuring the voltage at the battery?

 

[Furlo]

Whenever I've checked it it's been good, well over 12v. However, I don't know if the battery's voltage has been dropping for some reason - it's been sub zero, but I thought AGMs were fine with that.

I don't understand why the 12v won't come back online without a nudge from shore power...

 

[Phill D]

12.1v is just 50% charged 12.7v + is fully charged.
Try charging until your resting voltage is 12.7v plus, then checking the voltage each morning and noting the point at which the cut off appears to happen.
But this needs a multimeter to check voltage at the battery, unless you have a decent quality shunt and meter in line.

That may be the only way you can eliminate if your battery has had its day or discharged, or your habitation cut off is the problem.

 

[rb62]

When you plug the EHU in the 12v will work because it is getting the voltage from the charging unit,as said in previous post leave it on charge until the batteries are charged,disconnect the EHU then see how long they last.

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